The superfluid phases in resonant dipolar Fermi gases are investigated by the standard mean-field theory. In contrast to the crossover from Bose-Einstein condensation (BEC) to ...Bardeen-Cooper-Schrieffer superfluid in Fermi gases with isotropic interactions, resonant dipolar interaction leads to two completely different BEC phases of the tight-binding Fermi molecules on both sides of the resonance, which are characterized by two order parameters with distinct internal symmetries. We point out that, near the resonances, the two competitive phases can coexist, and an emergent relative phase between the two order parameters spontaneously breaks time-reversal symmetry, which could be observed in momentum resolved rf spectroscopy.
•Periodic instability on heat transfer is clarified.•Heat transfer is greatly enhanced with the increase of Re.•The process of taking away the hot fluid and bringing cold fluid is identified.
A ...three-dimensional incompressible numerical model for the case of the 3D backward-facing step flow is established to investigate the characteristics of fluid flow and heat transfer in the low and middle Reynolds number ranges (200 ≤ Re≤1400). The governing equations, including continuous, unsteady Navier–Stokes and energy equations, are solved by the finite volume method in FLUENT. The simulation results show that the time averaged reattachment length reaches the peak value at Re = 1000, and subsequently decreases as the increase of Re. The formation of secondary peak Nu influenced by flow instability has a better contribution to the heat transfer at the center area. Taking away the hot fluid and carrying the cold fluid into the floor wall, which is caused by periodic instability, have positive effects on heat transfer enhancement.
Recent ground‐based imager observations have provided evidence of precursor auroral activity leading to substorm auroral onset, where the precursor is initiated by a poleward boundary intensification ...(PBI) followed by an auroral streamer moving equatorward toward the onset latitude leading to substorm auroral onset. However, since many streamers do not lead to substorms, the question arises as to what conditions are required for streamers to lead to onset. Using 382 events detected by the THEMIS all‐sky imagers during 2007–2009, we examined the properties of latitudinally thin, quiet arcs that eventually break up during the substorm auroral onset and the relationship of such quiet arcs to streamers. We found that a pre‐existing latitudinally thin quiet arc that leads to auroral onset is much brighter than prior thin arcs that do not lead to onset, and that streamers that do not lead to onset form or intensify such quiet arcs. The newly formed or intensified quiet arc remains bright for a few to tens of minutes (∼20 min on average) until a subsequent streamer leads to substorm auroral onset along the pre‐existing arc. The pre‐onset sequence proposed here suggests that both types of streamers, which do and do not lead to substorms, enhance auroral luminosity near the equatorward boundary of the oval, and that a sufficiently intense, quiet time thin arc near the poleward edge of proton precipitation, likely corresponding to a large plasma pressure gradient in the near‐Earth plasma sheet, reflects important pre‐conditions for a precursor flow burst to trigger substorm auroral onset.
Key Points
The properties of latitudinally thin quiet arcs and streamers are examined
We found a difference in the quiet arc brightness during multiple streamers
We found that streamers without onset also enhance quiet arc intensity
A new field of dental medicine seeks to exploit nature’s solution for repairing damaged tissues, through the process of regeneration. Most adult mammalian tissues have limited regenerative ...capacities, but in lower vertebrates, the molecular machinery for regeneration is an elemental part of their genetic makeup. Accumulating data suggest that the molecular pathways responsible for the regenerative capacity of teleosts, amphibians, and reptiles have fallen into disuse in mammals but that they can be “jumpstarted” by the selective activation of key molecules. The Wnt family of secreted proteins constitutes one such critical pathway: Wnt proteins rank among the most potent and ubiquitous stem cell self-renewing factors, with tremendous potential for promoting human tissue regeneration. Wnt reporter and lineage-tracing strains of mice have been employed to create molecular maps of Wnt responsiveness in the craniofacial tissues, and these patterns of Wnt signaling colocalize with stem/progenitor populations in the rodent incisor apex, the dental pulp, the alveolar bone, the periodontal ligament, the cementum, and oral mucosa. The importance of Wnt signaling in both the maintenance and healing of these craniofacial tissues is summarized, and the therapeutic potential of Wnt-based strategies to accelerate healing through activation of endogenous stem cells is highlighted.
Transition metal (TM) doped II–VI semiconductors have attracted great attention due to their luminescence and diluted magnetism. In this study, the Fe3+-doped ZnSe nanobelts (NBs) were grown by a ...facile CVD method. The surface morphology observed via SEM is smooth and clean and the elemental composition measured via EDS confirms that the Fe3+ ions were incorporated into ZnSe NBs successfully. The micro-Raman scattering spectra demonstrate that the as-prepared NBs have the zinc blende structure. Furthermore, the Raman spectra of the Fe3+-doped NBs were compared with those of pure and Fe2+-doped reference samples. The former with a higher signal-to-noise ratio, an enhanced 2LO mode, a stronger LO mode redshift and a larger intensity ratio of LO/TO mode as well as the lower acoustic phonon modes confirms the better crystallization and the stronger electron–phonon coupling on Fe3+-incorporation. The emission of single Fe3+ ion, assigned to the 4T1 → 6A1 transition, was observed at about 570 nm. Moreover, increasing the doping concentration of Fe3+ ions caused the formation of different Fe–Fe coupled pairs in the lattice, which emitted light at about 530–555 nm for an antiferromagnetic-coupled pair, possibly due to the stacking faults and at about 620–670 nm for a ferromagnetic-coupled pair.
A series of rare earth compound nanotubes, including hydroxides, oxides, oxysulfides, and hydroxyfluorides, have been synthesized using a facile hydrothermal method. Owing to their excellent ...hydrophilicity, the nanotubes can be easily functionalized, and should offer new opportunities in areas such as optoelectronic and nanoscale devices, low dimensional physics and material science, molecular catalysts, and biological technology.
•Monoclinic WO3 films were prepared by pulsed laser deposition.•The WO3 films exhibited preferred (002) orientation at elevated temperature.•The structure and optical properties of WO3 films depended ...on substrate temperature.•The optical band gap of WO3 films decreased as substrate temperature increased.
Tungsten oxide (WO3) films were prepared on Si (100) and fused silica substrates by pulsed laser deposition (PLD). The effects of substrate temperature on the morphology, microstructure and optical properties of WO3 films were investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectra and UV–visible spectrophotometer. It was found that the microstructure, morphology and optical properties strongly depend on the substrate temperature. The X-ray diffraction and Raman results indicate that the amorphous WO3 films are obtained at substrate temperatures below 200°C whereas the films grown above 300°C exhibit predominantly (002) plane orientation, representing the monoclinic structure. The surface roughness, film crystallinity and grain size of the films increase with increasing substrate temperature. The films prepared at substrate temperatures ranging from 300 to 600°C exhibit high averaged transparency over 60% in the visible region. The optical band gaps of the films are found to decrease monotonically from 3.22 to 3.05eV as the substrate temperature increases from 200 to 600°C due to the crystallization of deposited WO3 film.
We study a sample of 17 z > 1.5 absorbers selected based on the presence of strong C I absorption lines in Sloan Digital Sky Survey (SDSS) spectra and observed with the European Southern Observatory ...Very Large Telescope (ESO-VLT) spectrograph X-shooter. We derive metallicities, depletion onto dust, and extinction by dust, and analyse the absorption from Mg II, Mg I, Ca II, and Na I that are redshifted into the near infrared wavelength range. We show that most of these C I absorbers have high metallicity and dust content. We detect nine Ca II absorptions with W(Ca IIλ3934) > 0.23 Å out of 14 systems where we have appropriate wavelength coverage. The observed equivalent widths are similar to what has been measured in other lower redshift surveys of Ca II systems. We detect ten Na I absorptions in the 11 systems where we could observe this absorption. The median equivalent width (W(Na Iλ5891) = 0.68 Å) is larger than what is observed in local clouds with similar H I column densities but also in z < 0.7 Ca II systems detected in the SDSS. The systematic presence of Na I absorption in these C I systems strongly suggests that the gas is neutral and cold, maybe part of the diffuse molecular gas in the interstellar medium of high-redshift galaxies. Most of the systems (12 out of 17) have W(Mg IIλ2796) > 2.5 Å and six of them have log N(H I) < 20.3, with the extreme case of J1341+1852 that has log N(H I) = 18.18. The Mg II absorptions are spread over more than Δυ ~ 400 km s−1 for half of the systems; three absorbers have Δυ > 500 km s−1. The kinematics are strongly perturbed for most of these systems, which indicates that these systems probably do not arise in quiet disks and must be close to regions with intense star-formation activity and/or are part of interacting objects. All this suggests that a large fraction of the cold gas at high redshift arises in disturbed environments.
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